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Breast cancer occurs when a cell within a breast undergoes changes that cause it to grow and divide uncontrollably. The tumour that develops from this will destroy tissue around it. Any tissue in the breast can be affected. Usually the cancer arises from tissue that forms milk ducts. Both women and men can develop breast cancer, but it is very rare in men.
What is going on in the body?
A tumour in the breast does not affect the bodily function of the breast. For example, the breast may remain sensually active, change with the menstrual cycle or pregnancy and even produce breast milk A tumour will cause destruction of tissue within the breast. Spread of the tumour to other parts of the body can cause death.
Before a cancer in the breast can be detected, it must grow large enough to either be felt or seen on special X-rays called a mammogram. Sometimes a tumour isn't found for many years.
The tumour may distort the shape of the breast or the texture of the skin as it becomes larger. This is because surrounding tissues become fixed to the tumour. The tumour will grow through the breast to the outer skin if left untreated.
Cancer cells can also enter specialised channels in the breast called lymphatics. These cells travel through the lymphatics to the lymph nodes where they form tumours. This most commonly occurs in lymph nodes under the armpit or within the chest. This may occur when the tumour has grown large, but can also happen sooner. Cancer cells can also spread to other parts of the body through the blood stream. This can occur when the tumour is large or small. These cells can travel to other tissues and form new tumours. Breast cancer is most often spread to the bones, lungs, brain, and liver, but any tissue can be affected.
What are the signs and symptoms of the disease?
Early in the disease, the only symptom may be a painless lump in the breast. This lump must be about the size of the fingertip before it can be felt. It can be anywhere in the breast. The lump is usually very hard and may not move when touched. Of the cancers not found by mammography, the woman herself finds the majority. A woman's best defence is to utilise monthly breast self-examination, or BSE, clinical examination and mammography in combination for early detection of breast cancer.
Later in the disease, the person may have swelling in the lymph nodes in the armpit. He or she can also have symptoms related to the spread of the cancer. For instance, breast cancer that has spread to the bone will cause pain in the affected area.
What are the causes and risks of the disease?
The risk for any woman to develop breast cancer is significant, about 1 in 11 over a lifetime. About 5% to 15% of all breast cancers may be related to genes that are passed through families called BRCA1 and 2 . Women may be at greater risk of developing this cancer if they:
There are other risk factors for developing breast cancer, but they are controversial. They include:
- started their periods early
- delay childbearing to later in life or have no children
- are treated for other cancers using radiation to the chest
- have close blood relatives, like a mother or sister, who develop breast cancer before menopause
- started menopause late
Women who breastfeed their children may lower their risk for breast cancer. However, a woman may have every risk factor and never develop breast cancer. A woman may have no risk factors and develop breast cancer. At this time it is not possible to predict who will and who will not develop breast cancer with absolute accuracy.
- drinking a moderate amount of alcohol
- eating a high-fat diet
- being obese
- using hormones such as oestrogen and progesterone
What can be done to prevent the disease?
No diet or other similar intervention has been found to prevent breast cancer in rigorous scientific studies. There are studies underway to see if certain drugs can prevent the development breast cancer in high risk women. The medications, including tamoxifen, are not expected to be 100% effective, and may have serious side effects. There is no other proven method to effectively prevent this cancer.
It is very important to detect breast cancer early when it is much easier to cure. This is best done by a woman checking her breasts once a month for any unusual lumps. A doctor should check the woman's breasts during routine physical examinations every 2 years. Recommendations vary for screening mammography depending on age of the individual and a family history of the disease along with categorisation of risk:
According to guidelines from the NHMRC National Breast Cancer Centre:
1. At or slightly above average risk
Covers over 95% of the female population
2. Moderately increased risk
- No confirmed family history of breast cancer
- One 1st or 2nd relative diagnosed with breast cancer at age 50 or older
- Two 1st or 2nd relatives diagnosed with breast cancer at age 50 or older, but on different sides of the family
- One 2nd relative diagnosed with breast cancer at any age
- practise monthly breast self examination (BSE)
- attend for annual clinical breast examination if aged 40 or older
- attend for 2 yearly screening mammogram if aged 50 or older, in line with the state policy of BreastScreen3
- visit her general practitioner promptly with any breast changes.
Covers less than 4% of the female population
3. Potentially high risk, Covers less than 1% of the female population
- One or two 1st relatives diagnosed with breast cancer before the age of 50 (without potentially high risk features - see 3)
- Two 1st or 2nd relatives on the same side of the family diagnosed with breast or ovarian cancer (without potentially high risk features - see 3)
- One should
- practise monthly BSE
- attend for annual clinical breast examination if aged 40 or older
- at the very least, attend for mammogram every 2 years if aged 50 or older, in line with the state policy of BreastScreen 3 Additional surveillance (eg. mammogram from a younger age or more frequently), should be considered on an individual basis as evidence about optimal strategies in this group does not currently exist.
- visit her general practitioner promptly with any breast changes
Emphasise the importance of early detection. Advise the woman to see a cancer specialist to plan an appropriate individualised surveillance programme which may include:
- Three or more 1st or 2nd relatives on the same side of the family diagnosed with breast or ovarian cancer
- Two or more 1st or 2nd relatives on the same side of the family with breast or ovarian cancer including any of the following high risk features: bilaterality, diagnosed at age 40 or younger, breast and ovarian cancer in one individual, or breast cancer in a male
- One 1st or 2nd relative diagnosed with breast cancer at age 45 or younger plus another 1st or 2nd relative on the same side of the family with sarcoma (bone/soft tissue) at age 45 or younger
- Member of a family in which the presence of a high risk breast cancer gene mutation has been established
How is the disease diagnosed?
- practise monthly breast self-examination
- attend for 6 monthly clinical breast examination
- mammography with or without other imaging technique
- surveillance for ovarian cancer for some women
- visit her general practitioner promptly with any breast changes
Lumps may be found by a woman or her partner, or by her doctor while physically examining the breast. Sometimes the lump cannot be felt, but is found on a screening mammogram.
After the lump is discovered, a tissue sample must be taken in order to find out if it is cancer. If the lump is seen only on mammogram, a needle is guided under X-ray to take a sample. Often the lump is removed through minor surgery. The tissue will be carefully studied to determine first if it is cancer. Then the tissue will be tested to see how aggressive the cancer is. Other tests will be done to determine factors that will affect treatment choices. The most common factors are:
A woman may also undergo other specialised X-rays to see if the cancer has spread beyond the breast.
- aggressiveness of the tumour cells
- sensitivity to oestrogen or progesterone
- the presence of certain proteins
What are the long-term effects of the disease?
This cancer is fatal if left untreated. It can be cured in the early stages. Once cured, the person will live a normal life. Loss of the breast may be emotionally upsetting. Reconstruction of the lost breast may assist with emotional adjustment.
What are the risks to others?
There are no direct risks to others. A breast cancer cannot be spread from person to person. When a young woman has breast cancer, this may indicate that other close female relatives are at risk. This does not mean that she will spread it.
What are the treatments for the disease?
Treatment depends on factors found when the tumour was diagnosed and how advanced the cancer is at that time. Early stage cancers can be cured. Advanced stage cancers can often be controlled for long periods. Except for very small ductal carcinomas in situ, or DCIS, most cancers will be treated with additional surgery after diagnosis.
DCIS are precancerous tumours that do not invade surrounding tissue. For these small tumours, only a lumpectomy is usually needed. This procedure removes any tumour left from biopsy and the surrounding tissue. Radiation therapy to the affected area will be required.
Larger or deep tumours may indicate that the whole breast must be removed. This operation is called a mastectomy. Lymph nodes under the arm on the affected side will be removed for testing. All the nodes may be removed at surgery. Or, only a few may be removed in a special procedure, called sentinel node biopsy, in which a dye is injected at the tumour site.
Examination of the breast tissue sample may result in one of these diagnosis:
What are the side effects of the treatments?
- Very early stage, low grade. These cancers are very small and in one location. For a diagnosis of DCIS, testing of the tumour would indicate that the tumour is not likely to have spread. In this case, removing just the affected part of the breast with a lumpectomy may be all that is required. Radiation therapy to the affected area may also be recommended.
- Early Stage, no involved nodes. If the cancer is not responsive to hormones, the woman may be offered chemotherapy. If the cancer is responsive to hormones, then a treatment to suppress hormone activity, including drugs like tamoxifen, will be offered. Both treatments are to ensure that any possible cancer left behind is killed or suppressed. Radiation therapy to the affected area may also be recommended.
- Early stage, positive nodes. Chemotherapy will be offered to kill any remaining undetectable cancer. Women whose cancer is responsive to hormones will also receive tamoxifen or similar antihormone drugs. The kind of chemotherapy and intensity of the regimen will be determined by other factors in the tumour. Radiation therapy to the affected area may also be recommended.
- Advanced stage. When the cancer has spread to nearby structures or to other areas of the body, the goal will be to control the cancer. Chemotherapy will be offered. Antihormone drugs can be given to women whose tumours are likely to respond. Other medication to treat problems caused by the advancing cancer will be used to relieve symptoms. Radiation therapy to the affected area may also be recommended.
Surgery: After surgery, the breast can be reconstructed. Reconstruction will restore the normal shape to the breast following lumpectomy or mastectomy. The nerves to the breast area may be cut and the area may remain numb. At first, movement may be restricted. Physiotherapy and exercise will restore complete function.
Radiation: Women may have fatigue while undergoing radiation but will completely recover. The skin over the affected area may be darkened and feel somewhat different than normal skin.
Chemotherapy: Side effects are specific to the drugs. Most are manageable and will resolve when treatment ends.
Antihormone therapy: These drugs may cause menopausal symptoms even in women who have already been through menopause. These symptoms usually subside with continued use.
What happens after treatment for the disease?
For people with early stage disease, the side effects of therapy will eventually subside. Those with advanced disease may require changes in therapy to keep the cancer in control.
How is the disease monitored?
After completing therapy, a person with early stage disease will receive regular monitoring from a doctor to make sure the cancer does not returned. This will include physical examinations, mammograms, and other tests. Over time, the frequency will decrease. For those whose cancer is advanced, more frequent monitoring of the progress of the disease and the effect of treatment is necessary. Tests, such as bone scans or CAT scans, will be used to follow the disease.
Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Potential conflict of interest information for reviewers available on request
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